Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
int n,m;
char s[55][55];
int w;
int sx,sy,gx,gy;
int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};
int d[55][55];
void bfs(){
	queue<P> que;
	que.push(P(sx,sy));
	while(que.size()){
		P p=que.front(); que.pop();
		if(p.first==gx&&p.second==gy) break;
		for(int i=0;i<4;i++){
			int nx=p.first+dx[i],ny=p.second+dy[i];
			if(0<=nx&&nx<n&&0<=ny&&ny<m&&s[nx][ny]!='#'&&d[nx][ny]==1000000000){
				que.push(P(nx,ny));
				d[nx][ny]=d[p.first][p.second]+1;
			}
		}
	}
}
int main(void){
	cin>>n>>m;
	for(int i=0;i<n;i++){
		for(int j=0;j<m;j++){
			cin>>s[i][j];
			if(s[i][j]=='.') w++;
			d[i][j]=1000000000;
		}
	}
	gx=n-1; gy=m-1;
	d[0][0]=0;
	bfs();
	if(d[n-1][m-1]==1000000000){
		cout<<-1<<endl;
		return 0;
	}
	//cout<<w<<" "<<d[n-1][m-1]<<endl;
	cout<<w-d[n-1][m-1]-1<<endl;
	
}